Studies On Nanostructural Anodic Catalysts For Direct Methanol Fuel Cell

Recently developed direct methanol fuel cell has been received widespread attention due to the abundant source, the low price, the safety of the storage and transportation of the fuel. Nevertheless, the step toward the practical application has not been developed as fast as had been expected. It is key techniques in DMFC to find with the complex catalysts have good electrocatalytic activity and resistant ability to poisoning for the methanol oxidation. The good electrocatalytic active nanoTiO2-CNT-Pt, nanoTiO2-CNT-PtNi,nanoTiO2-CNT-PtNiNd complex nanostructural catalysts were prepared by the precursor Ti(OEt)4 directly hydrolyzed and cyclic voltammetry electrodepositing method, using XRD and TEM techniques, the size and crystallinity of the catalysts. The electrocatalytic activitics and stability for the methanol oxidation were evaluated with the electrochemical techniques, The main result obtained are as follows:Part one: electrochemical deposition method by cyclic voltammetry(CV) to prepare the Ti/nanoTiO2-CNT-Pt, and the composite electrodes were characterized to study those composition and those electrochemical behavior by CV, The electrocatalytic activitics and stability for the methanol oxidation and the electrocatalystic activition of the electrodes for the oxygen reduction were evaluated with the electrochemical techniques. Using the XRD and TEM techniques . TEM results and XRD results indicated that the Pt microparticles were uniformly high dispersed on nanoTiO2-CNT films, nanoTiO2-CNT decreased catalytic agglomeration rate, and these made the Ti/nanoTiO2-CNT samples higher specific surface area of Pt. the size and the disperion degree of the catalyst particles were studied in presence or absence of nanoTiO2-CNT films in the catalyst. It was found that methanol oxidation was catalyzed on the nanoTiO2-CNT modified Pt by lowering methanol oxidation potential and promoting methanol oxidation current. The catalysts show high performance and good stability for theelectro-oxidation , which is the results of the co-operation effect of Pt and TiO2 â– . CNT particles and Pt and TiO2 particles have small particle diameters and can disperse.Part two: The Ti/nanoTiO2-CNT-PtNi composite electrode was prepared by cycling the potential between -0.8V and -0.05V versus SCE, at a scan rate of 50mV/s, in a solution of lOmM/L in H2PtCl6^ 30 mM/L in NiCl2. Chronoamperometry response and CV results for the Ti/nanoTiO2-CNT-PtNi composite electrode, compared with the Ti/nanoTiO2-CNT-Pt electrode, methanol oxidation took place on the nanoTiO2-CNT modified PtNi at the potential 20mV more negatively than on the nanoTiO2-CNT modified Pt, the steady mass specitic oxidation current of methanol on this modified platinum was 40%-60%. Pt: Ni atomic ratio of 1: 3 showed the highest electrocatalytic activity for methanol oxidation. The enhanced catalytic activity of nanoTiO2-CNT-Pt-Ni catalysts for methanol oxidation can be rationalized by a bifunctional mechanism in which Pt is responsible for dehydrogenation of methanol and metallic Ni for the dehydrogenation of water. It was also found that an electronic effect in the electrocatalysis is associated with the amount of Ni atoms in the catalysts.Part three: we putted Ti/nanoTiO2-CNT-PtNi composite electrode into a HC1 solution of 6.0 ml/L Nd3+ for half an hour, Chronoamperometry response and CV results for the Nd3+ modified Ti/nanoTiO2-CNT-PtNi composite electrode, showed slightly a better CO tolerant perfomance, Presence of Nd3+ in the Ti/nanoTiO2-CNT-PtNi composite electrode by electrochemical codeposition made peak potential of methanol oxidation a further negative shift of about 20mV and bigger peak current. The experimentas results show that Nd3+ has a high catalysis for electrocatalytic oxidation of methanol in electrolyte. A possible synthesis mechansm was proposed.The thesis studied preparation of some new nanostructural electrocatalytic electrodes with higher electro-catalytic activity and...